Global Experiments on Chemistry. Kapil Tripathi Scientist-D VIGYAN PRASAR(DST ). International Year of Chemistry 2011. Year 2011 has been declared as the International Year of Chemistry.
Global Experiments on Chemistry
VP is creating awareness about Global Experiments among the teachers to perform the
experiments in their schools.
This includes following four experiments:
Measuring pH -The two most common measurements of pH involve using indicators or pH meters.
Indicators are weak acids that are coloured and that change colour when they undergo an acid-base reaction and (formally) lose the H+ ion. The reactions are usually reversible so that the indicator has two molecular forms: the acid and the base:
bromothymol blue → bromothymol blue-
acid form base form
The colour change in indicators usually occurs across a 10-fold change in H3O+ concentration
and socovers a change in pH of one.
pH meters – Instrument which measure the pH using glass electrode. more.
Interpreting pH values
Testing the local water source
Chloride Cl-1 19.345
Sodium Na+1 10.752
Sulfate SO4-2 2.701
Magnesium Mg+2 1.295
Calcium Ca+2 0.416
Potassium K+1 0.390
Bicarbonate HCO3-1 0.145
Bromide Br-1 0.066
Borate BO3-3 0.027
Strontium Sr+2 0.013
Clarification is the process used to remove solid debris from
natural or waste water and involves four steps:
(use 500 mL of your filtered water for this activity).
% water purified = volume collected X 100
Volume added to still